Vehicle wheel transmission

ABSTRACT

A vehicle transmission comprising a vehicle chassis ( 10 ), a hub unit ( 20 ) for a driven wheel; a chassis mounted drive motor assembly ( 11 ) individual to the hub unit and pivoted to the chassis about an axis ( 12 ) passing through or adjacent to the center of gravity of the motor assembly; a shaft assembly connecting the drive motor assembly to a rotatable part ( 25 ) of the hub unit and comprising a shaft ( 31 ) connected to a fixed, constant-velocity, universal joint ( 26 ) at the outboard end of the shaft which is drivingly connected to the rotatable part of the hub unit; a wheel suspension ( 22, 23 ) connected between a non-rotatable part ( 21 ) of the hub unit and the chassis ( 10 ); and a rigid tube ( 19 ) connnecting the non-rotatable part of the hub unit to the motor assembly, the non-rotatable part ( 21 ) of the hub unit being pivotally mounted with respect tot the tube about the center of articulation of the universal joint and the shaft lying within said tube and being rigidly connected to the motor assembly.

TECHNICAL FIELD

This invention relates to vehicle transmissions and in particular totransmissions of the type wherein each driven wheel is driven by aseparate motor. The motor may be electric, hydraulic or pneumatic.

BACKGROUND ART

Previously, in vehicles which have been driven by individual electricmotors, either the electric motor has been connected directly to thewheel and is carried by the suspension as, for example, in U.S. Pat. No.5,322,141 or, as shown in FIG. 2 of U.S. Pat. No. 5,679,087, theelectric motors have been mounted rigidly on the vehicle chassis andconnected to the driven wheels by drive shafts having a universal jointat each end.

The former construction increases the unsprung mass of the vehicle.

The object of the invention is to provide a vehicle transmission whereinone or more wheels is driven by its individual motor which may, forexample, be electric but in which the motor is mounted on the chassis orsupport thus keeping the unsprung mass to a minimum but in which thereis a simplified drive from the motor to the wheel and a simplifiedsuspension linkage.

DISCLOSURE OF THE INVENTION

According to the invention we provide a vehicle transmission comprisinga support, a hub unit for a driven wheel; a drive motor assemblyindividual to the hub unit and mounted on the support adjacent to thehub unit; a shaft assembly connecting the drive motor assembly to arotatable part of the hub unit and comprising a shaft connected to afixed, constant-velocity, universal joint at the outboard end of theshaft which is drivingly connected to the rotatable part of the hubunit; a wheel suspension connected between a non-rotatable part of thehub unit and the support; and a rigid tube connecting the non-rotatablepart of the hub unit to the motor assembly, said non-rotatable partbeing pivotally mounted with respect to the tube about the center ofarticulation of the universal join; the shaft lying within said tube andbeing rigidly connected to the motor assembly, i.e. without anyarticulated joint, and the motor assembly being pivoted to the supportabout an axis passing through or adjacent to the center of gravity ofthe motor assembly.

Preferably the motor assembly is pivoted to the support in resilientbearings. Normally the hub will be steerable and the non-rotatable partof the hub unit pivoted with respect to the outer end of the tube. Theouter end of the tube may be formed with an enlarged portion with aninternal spherical surface, the non-rotatable part of the hub unithaving a spherical portion which fits within said surface in a pivotalmanner and wherein the centers of the spherical surfaces are coincidentwith the center of articulation of the universal joint.

Alternatively the outer end of the tube may be formed with a first armwhich is pivoted to a curved arm to which the non-rotatable part of thehub unit is pivoted so that the pivotal axes of the connections betweenthe arms and between the second arm and said non-rotatable partintersect at the center of articulation of the joint.

Normally the motor assembly will include a reduction gear and the motormay, be an electric, hydraulic or pneumatic motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a vehicle transmission constituting a firstembodiment of the invention;

FIG. 2 is a plan view of the embodiment shown in FIG. 1; and

FIG. 3 is a composite sectional view of a second embodiment of theinvention, the upper part being a vertical section and the lower partbeing a horizontal section.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring first to FIGS. 1 and 2, part of a vehicle chassis is shown at10. Pivoted to the chassis 10 is an electric motor assembly 11 whichincludes a reduction gear. The assembly 11 is pivoted about an axis 12which passes through or adjacent to its center of gravity. The motorassembly is pivoted in two similar flexible bearings each of whichcomprises a ball 13 secured to the motor assembly and received in ashaped sleeve 14. The sleeve 14 in turn is received in a bore 15 in abracket 16 provided with a flange 17 for connection to the chassis 10.

Extending from the motor assembly 11 is a rigid tube 18 which has acurved arm 19 extending transversely from its outer end and beingprovided with a bore 19 a which is parallel to the axis 12. A hub unitis indicated at 20 and includes an outer part 21 which forms part of aknuckle 22 which is connected to the vehicle suspension indicateddiagrammatically at 23. The hub unit 20 contains a bearing 24 in whichis mounted a wheel hub 25 to carry a driven road wheel, not shown. Thehub 25 is connected to the outer part 26 a of a fixed constant velocityjoint 26. The outer part 26 a has a spigot 27 which passes through asplined bore 28 In the hub and is formed over at 29 to hold It in place.One end of an arm 32 is pivoted to the curved arm 19 about an axisparallel to the axis 12 by a pin 30. The fixed part 21 of the hub unit20 has a vertical spigot 34 which engages in a bore 32 a in the otherend of the arm 32 to pivot the fixed part 20 to the arm 19 about an axisperpendicular to the axis 12. The pivot axes of the pin 30 in the bore19 a and the spigot 34 in the bore 32 a intersect at the center ofarticulation of the constant velocity joint 26. This arrangement allowssuspension movement when the motor assembly 11 rotates around the axis12.

A shaft 31 is connected to the rotor of the motor assembly 11 and at itsouter end is connected to the inner part, not shown, of the constantvelocity joint 26. The inner part drives the outer part 26 a in thenormal manner allowing articulation of the hub relative to the tube 18and motor assembly 11. The, knuckle 22 can be steered about the spigot34 by means of a steering arm 33 connected to the fixed part 21 of thehub unit.

It will be seen, therefore, that the assembly of the motor 11, the tube18 with its arm 19, the curved, arm 32 and the fixed part 21 of the hubunit together form a link assembly of the vehicle suspension, the part21 being connected to the suspension 23 through the knuckle 22. Thismakes a very light and simple arrangement where the wheels are driven bytheir individual motors. As mentioned above the axis of the pin 30 andthe axis of the spigot 34 intersect at the articulation center of thejoint 26.

Referring now to FIG. 3, an electric motor assembly is indicated at 35and as before includes an electric motor and a reduction gear box. Themotor is mounted to the chassis (not shown) by bearings 36 similar tothose described in relation to FIGS. 1 and 2. A tube 38 extendsoutwardly from the motor assembly 35 and at its outer end is providedwith an enlarged portion 39 which provides a spherical inner surface 40.Mounted within the spherical surface 40 is an externally sphericalmember 41 which is free to move within the enlarged member 39 with theinner and external spherical surfaces in contact. A shaft 38 a is drivenby the motor and is connected to the inner member, not shown, of a fixedconstant velocity joint 42. The outer member 43 of the constant velocityjoint is connected as described in relation to FIGS. 1 and 2 to a hub 44which can receive a road wheel. The hub 44 is mounted in a bearing 45within the spherical member 41 so it is free to rotate therein. The hubcan be steered by pivoting the spherical member 41 within the portion 39by means of a steering arm 46. The centers of the spherical surfaces onthe members 39 and 41 are coincident with the articulation center 42 aof the joint 42.

The spherical member 41 is also connected to a knuckle 47 which in turnis connected to the vehicle suspension as in FIG. 1 and 2. The enlargedmember 39 has a slot 48 through which the knuckle passes to allow forsuspension movement.

The operation is as described in relation to FIGS. 1 and 2 thus themotor assembly 35 being pivoted about an axis 49 which passes through oradjacent to its center of gravity by means of supports 36 forms with thetube 38 and the member 39 one link of the suspension and the other linkof the suspension is formed by the spherical member 41 and the knuckle47. As before the hub 44 is driven via the shaft 38 a and the constantvelocity joint 42. The arrangement provides a simple and effective driveand suspension arrangement where each wheel is to be driven by its ownelectric motor.

In each embodiment the motor assembly 11 or 35 is pivoted about oradjacent to its center of gravity and is therefore balanced and thistherefore reduces the unsprung mass of the wheel and knuckle.

Although the motor assembly in each case has been described as beingpivoted about its center of gravity it could also be pivoted about thecenter of gravity of the combined motor assembly, tube, constantvelocity joint, hub etc. so as to further reduce the unsprung weight. Inany event the assembly is substantially balanced. In some circumstanceshowever it may be advantageous for the assembly to be slightlyunbalanced in a direction effectively to reduce the unsprung weight.

It will be seen that the invention provides an improved arrangement forindividual driving and suspension of vehicle wheels. The motors used maybe electric, hydraulic or pneumatic. The invention is primarily intendedto be used in road vehicles but may find other applications. Theinvention reduces the inertia of the wheel assembly and therefore allowsthe shock absorbers to work more efficiently.

1. A vehicle transmission comprising: a support, a hub unit for a drivenwheel; a drive motor assembly individual to the hub unit and mounted onthe support adjacent to the hub unit; a shaft assembly connecting thedrive motor assembly to a rotatable part of the hub unit and comprisinga shaft connected to a constant-velocity, universal joint at an outboardend of the shaft which is drivingly connected to the rotatable part ofthe hub unit; a wheel suspension connected between a non-rotatable partof the hub unit and the support; and a rigid tube connecting thenon-rotatable part of the hub unit to the motor assembly, saidnon-rotatable part being pivotally mounted with respect to the tubeabout the center of articulation of the universal joint, the shaft lyingwithin said tube and being rigidly connected to the motor assembly, andthe motor assembly being pivoted to the support about an axis passingthrough or adjacent to the center of gravity of the motor assembly.
 2. Atransmission according to claim 1 wherein the motor assembly is pivotedto the support in resilient bearings.
 3. A transmission according toclaim 1 wherein the hub is steerable and the non-rotatable part of thehub unit is pivoted about a center of articulation of the universaljoint.
 4. A transmission according to claim 3 wherein an outer end ofthe tube is formed with an enlarged portion with an internal sphericalsurface, the non-rotatable part of the hub unit having a sphericalportion which fits within said internal spherical surface in a pivotasmanner, the centers of the spherical surfaces being coincident with thecenter of articulation of the universal joint.
 5. A transmissionaccording to claim 3 wherein an outer end of the tube is formed with afirst arm to which is pivoted a curved arm to which the non-rotatablepart of the hub is pivoted and wherein the pivotal axes of theconnections between the arms and between the second arm and saidnon-rotatable part intersect at the center of articulation of the joint.6. A transmission according to claim 1 wherein the motor assemblyincludes a reduction gear.
 7. A transmission according to claim 1wherein the motor assembly includes an electric, hydraulic or pneumaticmotor.
 8. A transmission according to claim 2 wherein the hub unit issteerable and the non-rotatable part of the hub unit is pivoted about acenter of articulation of the universal joint.
 9. A transmissionaccording to claim 8 wherein an outer end of the tube is formed with anenlarged portion with an internal spherical surface, the non-rotatablepart of the hub unit having a spherical portion which fits within saidinternal spherical surface in a pivotal manner, the centers of thespherical surfaces being coincident with the center of articulation ofthe universal joint.
 10. A transmission according to claim 8 wherein anouter end of the tube is formed with a first arm to which is pivoted acurved arm to which the non-rotatable part of the hub is pivoted andwherein the pivotal axes of the connections between the arms and betweenthe second arm and said non-rotatable part intersect at the center ofarticulation of the joint.
 11. A transmission according to claim 8wherein the motor assembly includes an electric, hydraulic or pneumaticmotor.
 12. A transmission according to claim 9 wherein the motorassembly includes an electric, hydraulic or pneumatic motor.
 13. Atransmission according to claim 10 wherein the motor assembly includesan electric, hydraulic or pneumatic motor.